Biomedical subjects

Osama Mansour

Publications and source records attributed to Osama Mansour.

6 recordsLinked to original sources

PubMed2006

A prospective multivariate analysis of factors predicting stone disintegration by extracorporeal shock wave lithotripsy: the value of high-resolution noncontrast computed tomography.

OBJECTIVE: To assess the value of noncontrast computed tomography (NCCT) as a possible predictor of renal stone disintegration by shock wave lithotripsy (SWL). PATIENTS AND METHODS: The study included 120 consecutive patients (71 males, 49 females; mean age: 42.6 yr) with a solitary renal stone of 0.5-2.5 cm in length. NCCT was performed using a multidetector row CT scanner at 120 KV and 240 mA, with 1.25-mm collimation. A bone window was used to measure stone attenuation values. SWL was performed with an electromagnetic lithotripter. Failure of disintegration was defined as no fragmentation of the stone after three sessions. The impact of patients' sex, age, and body mass index (BMI) and the stones' laterality, location, volume, mean attenuation value, and the skin-to-stone distance on disintegration were evaluated by univariate and multivariate analyses. RESULTS: Failure of disintegration was observed in 15 patients (12.5%). BMI and stone density >1000 HU were the significant independent predictors of failure (p=0.04 and 0.02, respectively). The success rate of extracorporeal SWL at 3 mo was 87.5% (105 of 120 patients); 90 patients were stone free and 15 had residual fragments<4 mm. The only significant predictor of residual fragments was stone density (p<0.001). CONCLUSIONS: Obesity and increased stone density as detected by NCCT are significant predictors of failure to fragment renal stones by SWL. An alternative treatment should be devised for obese patients with stone density>1000 HU.

Adult↗

PubMed2006

Magnetic resonance urethrography in comparison to retrograde urethrography in diagnosis of male urethral strictures: is it clinically relevant?

OBJECTIVE: To compare the clinical relevance of retrograde urethrography (RUG) and magnetic resonance (MR) urethrography in evaluating male urethral strictures. METHODS: Between January and April 2004, 20 men were referred to our institute for management of urethral strictures. The patients were investigated by conventional RUG and multiformat MR urethrography. The patients were examined by urethroscopy under anesthesia to be followed by definitive endoscopic or open operative intervention. The radiologic data were compared by endoscopic as well as operative findings in all the patients. RESULTS: Ten patients were managed by visual internal urethrotomy (VIU) and two by dilatation under anesthesia; two showed normal urethral caliber. Four patients required open urethral reconstructive procedures. Two patients underwent radical cystectomy and cutaneous diversion because of associated bladder or urethral malignancy. Although overall accuracy for diagnosis of urethral strictures was equal between both modalities (85%), MR urethrography provided extra clinical data in seven patients (35%). It was superior to RUG in judging the urethral stricture length in three patients, diagnosing a urethral tumor in one, detecting associated bladder mass in one, characterizing the site of urethra-rectal fistula in one, and accurately delineating the proximal urethra in the last patient. Unlike RUG, MR urethrography provided adequate information about the degree of spongiofibrosis in all patients. CONCLUSION: MR urethrography is a promising tool for defining male urethral strictures and can provide extra guidance for treatment planning that cannot be obtained with RUG.

Adolescent↗

PubMed2005

Determination of the chemical composition of urinary calculi by noncontrast spiral computerized tomography.

Various techniques for noncontrast spiral computerized tomography (NCCT) were utilized for the determination of the Hounsefield unit (HU) values of various types of urinary calculi with the aim of determining the best technique for distinguishing various stones compositions. A total of 130 urinary stones, obtained from patients who underwent open surgery, were scanned with a multidetector row scanner using 1.25 mm collimation at two energy levels of 100 and 120 kV at 240 mA. Two post-scanning protocols were used for the HU value assignment, tissue and bone windows, for both kV values. In both protocols, three transverse planes were defined in each stone, one near the top, one in the middle, and one near the bottom. Three regions of interest (ROI) were obtained in each plane. The absolute HU value was determined by three methods: the mean of the nine ROI, the mean of the central three ROI, and the central ROI in the middle plane. Determination of the stones' composition was performed using the absolute HU value measured at 120 kV, the dual CT values (HU values at 100 kV-HU values at 120 kV), and HU values/stone volume ratio (HU density). All stones were analyzed by x-ray diffraction to determine their chemical composition. After the exclusion of groups with few calculi, 47 pure stones [25 uric acid (UA), 15 calcium oxalate monohydrate (COM), seven struvite], and 60 mixed stones [15 COM 60-90%+hydroxyl apatite (HA), 14 COM 40-90%+UA, 21 UA+COM <40%, ten mixed struvite+COM+hydroxyl apatite] were included in the statistical analysis. From the least to the most dense, the pure stone types were UA, struvite, COM. Mixed UA+COM<40% calculi were less dense but insignificantly different from pure UA, while when the COM ratio was > or =40% their density became higher than and significantly different from pure UA, and less than but not significantly differentiated from pure COM. Mixed COM+HA were the most dense stones. Using the absolute HU values at 120 kV and HU density, we could distinguish, with statistical significance, all pure types from each other, pure UA from all mixed calculi except UA+COM <40%, pure COM from mixed UA+COM <40%, and pure struvite from all mixed stones except mixed struvite stones. Dual CT values were not as good as absolute HU values and HU density in the determination of stone composition. These results demonstrate that absolute HU values and HU density derived from CT scanning using a small collimation size could uncover statistically significant differences among all pure and most of the mixed urinary stones. This permits more accuracy in the prediction of stone composition. Moreover, this technique permits diagnostic conclusions on the basis of single CT evaluation.

Humans↗

PubMed2004

Diagnosis of noncalcareous hydronephrosis: role of magnetic resonance urography and noncontrast computed tomography.

OBJECTIVES: To evaluate the role of magnetic resonance urography (MRU) and noncontrast computed tomography (NCCT) in the diagnosis of noncalcareous hydronephrosis when excretory urography (intravenous urography) is either contraindicated or inconclusive. METHODS: A total 108 consecutive patients with noncalcareous hydronephrosis were included in this study. In all patients, intravenous urography was either contraindicated or could not determine the diagnosis. In all patients, calculus obstruction was excluded by NCCT and all underwent heavily T2-weighted MRU. The final definitive diagnosis was established by retrograde or antegrade ureterography, endoscopy, or open surgery and was considered the reference standard for the diagnosis of obstruction. Normal kidneys in patients with unilateral obstruction were considered the reference standard for the absence of obstruction. The results of MRU were compared with those of NCCT regarding sensitivity, specificity, and overall accuracy. RESULTS: Of the 108 patients, 5 had bilateral obstruction and the remaining 103 had unilateral obstruction. Of the latter group, 5 had a solitary kidney; therefore, the total number of renal units was 211 (113 obstructed and 98 normal units). Ureteral strictures were identified by NCCT in 15 (28%) of 54 and by MRU in 45 (83%) of 54 patients. Bladder, ureter, or prostate tumors causing ureteral obstruction could be diagnosed in one half of the 54 patients with such tumors by NCCT (27 of 54) and in all but 2 patients by MRU (52 of 54). Both NCCT and MRU could identify all extraurinary causes of obstruction. Overall, of the 113 kidneys with noncalculus obstruction, the cause could be identified by MRU in 102 (sensitivity of 90%) and by NCCT in 47 (sensitivity of 42%), a difference of statistically significant value in favor of MRU (P <0.001). The specificity of T2-weighted MRU and NCCT was 100% and 99%, respectively (not a statistically significant difference). The overall accuracy of T2-weighted MRU and NCCT was 95% and 68%, respectively (P <0.001). CONCLUSIONS: In patients with ureteral obstruction in whom intravenous urography is not helpful and after NCCT has excluded stone disease, heavily T2-weighted MRU is a sensitive and specific method in the identification of the cause of obstruction.

Adult↗

PubMed2004

Diagnosis of ureteral obstruction in patients with compromised renal function: the role of noninvasive imaging modalities.

UNLABELLED: We compared the role of noncontrast computerized tomography (NCCT), magnetic resonance urography (MRU), and combined abdominal radiography (KUB) and ultrasonography (US) in the diagnosis of the cause of ureteral obstruction in patients with compromised renal function. MATERIALS AND METHODS: The study included 149 patients, of whom 110 had bilateral obstruction and 39 had obstruction of a solitary kidney. Therefore, the total number of renal units was 259. All patients had renal impairment with serum creatinine greater than 2.5 mg/dl. Besides conventional KUB and US all patients underwent NCCT and MRU. The gold standard for diagnosis of the cause of obstruction included retrograde or antegrade ureterogram, ureteroscopy and/or open surgery. The sensitivity, specificity and overall accuracy of NCCT, MRU, and combined KUB and US in the diagnosis of ureteral obstruction were calculated in comparison with the gold standard. RESULTS: The definitive cause of ureteral obstruction was calculous in 146 and noncalculous in 113 renal units, including ureteral stricture in 65, bladder or ureter in 43, extraurinary collection in 3 and retroperitoneal fibrosis in 2. The site of stone impaction was identified by NCCT in all 146 renal units (100% sensitivity), by MRU in 101 (69.2% sensitivity), and by combined KUB and US in 115 (78.7% sensitivity) with a difference of significant value in favor of NCCT (p <0.001). Ureteral strictures were identified by NCCT in 18 of the 65 cases (28%) and by MRU in 54 of 65 (83%). Bladder and ureteral tumors causing ureteral obstruction could be diagnosed in approximately half of the patients by NCCT (22 of 43) and in all except 1 by MRU (42 of 43). NCCT and MRU could identify all extraurinary causes of obstruction. Overall of the 113 kidneys with noncalculous obstruction the cause could be identified by MRU in 101 (89% sensitivity), by NCCT in 45 (40% sensitivity), and by combined KUB and US in only 20 (18% sensitivity) with a difference of significant value in favor of MRU (p <0.001). CONCLUSIONS: In patients with renal impairment due to ureteral obstruction NCCT has superior diagnostic accuracy for detecting calculous causes of obstruction but MRU is superior for identifying noncalculous lesions.

Adult↗

PubMed2002

Noncontrast computed tomography in obstructive anuria: a prospective study.

OBJECTIVES: To evaluate the role of noncontrast computed tomography (NCCT) in the determination of the cause of obstructive anuria and to compare its accuracy with that of the traditional methods of combined plain abdominal x-ray (KUB) and gray-scale abdominal ultrasonography (US). METHODS: The study included 40 consecutive patients with obstructive anuria. In addition to the routine evaluation, which included history, clinical examination, biochemical profile, KUB, and US, all patients underwent NCCT. The study patients were tested against an age and sex-matched control group that included the normal contralateral kidneys of 57 consecutive patients who underwent KUB, US, and NCCT for acute flank pain during the same study period. The reference standard for the determination of the cause of obstruction was retrograde or antegrade ureterography with or without ureteroscopy or open surgery. The absence of obstruction in the control group was confirmed by nonequivocal normal intravenous urography of the side free of flank pain. Both NCCT and combined KUB and US were compared regarding the sensitivity, specificity, and overall accuracy. RESULTS: The study group had 48 renal units, because obstruction was bilateral in 8 patients and of a solitary kidney in 32. Of the 42 renal units with calculus obstruction, the site of stone impaction was identified in all renal units by NCCT (sensitivity 100%) and in only 25 by combined KUB and US (sensitivity 59.5%)-a significant difference (P = 0.0001). Of the 6 renal units with noncalcular obstruction, both NCCT and US diagnosed the cause of obstruction in 3. The overall sensitivity of NCCT in the determination of the cause of obstructive anuria was 94% and that of combined KUB and US was 58%-a significant difference (P = 0.0001). The specificity of NCCT was not significantly different from that of combined KUB and US (96.5% versus 93%, respectively). The overall accuracy of NCCT was 95% and that of combined KUB and US was 77%-a significant difference (P = 0.0003). CONCLUSIONS: In patients with obstructive anuria, conventional KUB and US could not identify the cause of ureteral obstruction in about 40% of the patients. Under such conditions, NCCT can accurately provide the diagnosis, obviating the need of invasive and expensive diagnostic procedures.

Anuria↗